The Physicochemical Properties Of Semi-coke Of UCG And Its Purification Of Groundwater Pollution

In this paper,the simulation gasification experiments are completed by using a tube furnace simulation system and self-developed UCG simulation test system.The effects of gasification agent type,gasification temperature,residence time and coal rock?shale,sandstone and limestone?on the physicochemical properties of semi-coke are studied by N₂ physical adsorption analyzer,FTIR,and SEM so on.The physicochemical properties of gasification"three zone"residues also are analyzed.In addition,combine with physicochemical properties of chars,the adsorption characteristics of phenol and Cr???of semi-coke were investigated and its adsorption isotherm model and kinetic characteristic in adsorption process are also studied.The main contents and achievment are as follows:?1?Semi-coke produced by tubular furnace at different gasification process have abundant surface functional groups,large specific surface area and pore volume,and developed pore structure,which are mainly composed of narrow slit,round hole and flake like structure.Compared with the gasifying agent,gasification temperature,residence time and coalification degree have a significant effect on pore structure of semi coke.Different kinds of coal,the lower the degree of coalification,the char pore structure is developed;the same kind of coal,semi-coke have developed pore structure when gasification agent is H₂O,gasification temperature is 900^oC and residence time is1.5h,and its specific surface area and total pore volume are 657.6 m²/g and 0.562cm³/g,respectively.With coalification degree increased,gasification temperature rised and residence time prolonged,the degree of graphitization and aromatic nucleus condensation and the content of functional groups of semi coke showed the trend of increasing first and then decreasing.Besides,the removal of phenol on semi-coke is better than Cr???,and the removal effect are closely related to pore structure,surface chemical properties and phase composition.?2?Surrounding rock have an important influence on the structure and properties of gasified semi-coke.sandstone and shale have a weak influence on char pore structure change of Inner Mongolia,and when their content are too high,it is not conducive to pore structure developed of semi-coke;limestone is not conducive to pore structure developed of Hebi semi-coke,but can promote the mesoporous developed of Inner Mongolia semi-coke and micropore developed of Jiaozuo semi-coke.Coal rock may inhibit char structure to graphitization direction in a certain extent,and reduce the degree of aromatic condensation.Adsorption experiments showed that semi-coke from limestone and lignite mixed gasified have good adsorption properties on phenol and Cr???.With the increase of limestone content,the effect of adsorption is better.Langmuir adsorption isotherm model and pseudo two stage adsorption kinetic models can well describe the adsorption process of phenol and Cr???.?3?The physicochemical properties of"three zones"residues from UCG are different,with less surface functional groups,and the pore structure are not developed,and the specific surface area and total pore volume are not more than 60 m²/g and 0.05cm³/g.The"three zone"residue of UCG has a certain effect on the removal of phenol and Cr???from simulated wastewater and gas washing water,but the two are different.Removal of phenol:reduction zone>drying carbonization zone>oxidation zone;removal of Cr???:oxidation zone>reduction zone>dry distillation zone.